Field of the Invention
The invention relates to a method and apparatus for producing a superconducting connecting line as well as a line produced according to the method.
Oxide superconductors having a transition temperature so high that cooling with liquid nitrogen is sufficient to assure superconduction are known. Previously, these oxides were generally produced by means of powder metallurgy. However, these oxides are quite brittle and thus can only be formed with great difficulty. Accordingly, connecting lines that are to be used to supply public electric utility cannot be made solely from the known oxides. For instance, a metal base having an oxide film applied thereto is better suited for making a connecting line. However, if the oxide is applied to the base using conventional methods there is no compressive stress in the oxide film. Therefore unequal thermal expansion can produce cracks in the oxide film, which hinder or even interrupt continuous superconduction.
Consequently, the application of a finished oxide onto a foundation is not feasible if the connecting line produced in this way is not accessible at all points afterward. Yet such is the case if the connecting line is laid or run over large distances. A further consideration is that below-ground laying or placement of the line should also be possible.
It is accordingly an object of the invention to provide a superconducting connecting line and a method and apparatus for producing the same, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known methods and devices of this general type, in which adhesion of the oxide film to the base is assured by compressive stress and which can be used for supplying electricity for public utilities. Very good adhesion of the oxide film to a substrate should be assured, so that interruptions in the superconduction are kept to a minimum. In particular, the method should also be usable for easy repair of an already-installed, laid or run connecting line after a defect has occurred.